1. Field of Invention
The present invention relates to a process using radio-frequency microwave energy for the destruction of contaminated water-based liquids via a two stage alternating destruction and adsorption cycles.
2. Background
In today's modern world much contaminated material is generated. Such contaminated waste often is present as a water-based liquid after a washing process, and may contain, among other contaminants, chemical and biological agents that are harmful to humans. Thus disposal is a safety problem, and further such largely water residual is often required for recycled use, such as for cyclic washing of contaminated vehicles.
In the modern war on terrorism contamination of vehicles with chemical and biological agents is a real possibility and the subject process represents a viable way for cleaning such vehicles while destroying such agents and safely recycling the wash water.
The subject process employs microwaves to destroy such contaminants that occur in the form of organic chemicals and biological materials. To further enhance the effect of microwaves at low temperatures, carbonaceous material is employed that selectively absorbs microwaves in the presence of water, and selectively adsorbs the contaminants from the water when microwaves are absent. Additionally this process keeps the bulk temperature down to a modest level below about 200° F.
It is noted that chemical agents and biological agents are a special class of chemicals and are not identical to a hazardous material classification. Chemical agents are commonly related to “poisonous gaseous” and other such chemical compounds and are often employed in warfare or terrorist activities. In World War I mustard gas, C4H8Cl2S, was so employed as was cyanide gases
Biological agents although composed of organic molecules in a microorganism form have a special designation of being able to severely and usually fatally attack living organisms. Anthrax spores are such a biological agent and are employed in terrorist activities. Such biological agents are potentially carried by gas or liquid streams or may be washed from materials, such as cloth, metals, or other solids.
Yet the subject invention being a two-stage destruction—adsorption process alternatively employing microwaves can effectively process not only chemical and biological agents but also many hazardous materials.
Quantum radiofrequency (RF) physics is based upon the phenomenon of resonant interaction with matter of electromagnetic radiation in the microwave and RF regions since every atom or molecule can absorb, and thus radiate, electromagnetic waves of various wavelengths. The rotational and vibrational frequencies of the electrons represent the most important frequency range. The electromagnetic frequency spectrum is usually divided into ultrasonic, microwave, and optical regions. The microwave region is from 300 megahertz (MHz) to 300 gigahertz (GHz) and encompasses frequencies used for much communication equipment. For instance, refer to Cook, Microwave Principles and Systems, Prentice-Hall, 1986.
Often the term microwaves or microwave energy is applied to a broad range of radiofrequency energies particularly with respect to the common heating frequencies, 915 MHz and 2450 MHz. The former is often employed in industrial heating applications while the latter is the frequency of the common household microwave oven and therefore represents a good frequency to excite water molecules. In this writing the term “microwave” or “microwaves” is generally employed to represent “radiofrequency energies selected from the range of about 500 to 5000 MHz,” since in a practical sense this large range is employable for the subject invention.
The absorption of microwaves by the energy bands, particularly the vibrational energy levels, of atoms or molecules results in the thermal activation of the nonplasma material and the excitation of valence electrons. The nonplasma nature of these interactions is important for a separate and distinct form of heating employs plasma formed by arc conditions at a high temperature, often more than 3000° F., and at much reduced pressures or vacuum conditions. For instance, refer to Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Edition, Supplementary Volume, pages 599-608, Plasma Technology. In microwave technology, as applied in the subject invention, neither of these conditions is present and therefore no plasmas are formed.
Microwaves lower the effective activation energy required for desirable chemical reactions since they can act locally on a microscopic scale by exciting electrons of a group of specific atoms in contrast to normal global heating which raises the bulk temperature. Further this microscopic interaction is favored by polar molecules whose electrons become easily locally excited leading to high chemical activity; however, nonpolar molecules adjacent to such polar molecules are also affected but at a reduced extent. An example is the heating of polar water molecules in a common household microwave oven where the container is of nonpolar material, that is, microwave-passing, and stays relatively cool.
In this sense microwaves are often referred to as a form of catalysis when applied to chemical reaction rates; thus, in this writing the term “microwave catalysis” refers to “the absorption of microwave energy by carbonaceous materials when a simultaneous chemical reaction is occurring” For instance, refer to Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Edition, Volume 15, pages 494-517, Microwave Technology.
Related United States microwave patents include:
U.S. Pat. No.InventorYear6,045,663Cha20006,046,376Cha et al.20006,187,988Cha2001
Referring to the above list, Cha '663 discloses the enhancement of wet oxidation by microwaves utilizing carbonaceous material. Wet oxidation involves a water medium saturated with oxygen and containing organic contaminants, such as hazardous solvents, but not containing biological material. The process employs only a single microwave irradiated reactor containing carbonaceous material. The process shows that such carbonaceous material, often activated carbon, preferentially absorbs microwaves in the presence of water.
Cha et al. disclose the enhancement of gaseous decomposition from a solution by microwaves utilizing carbonaceous material. An important example is the wet calcination of bicarbonate solutions, such as trona. The decomposition reaction is restricted to inorganic chemicals. The process employs only a single microwave irradiated reactor containing carbonaceous material. The process shows that such carbonaceous material, often activated carbon, preferentially absorbs microwaves in the presence of water.
Cha '988 discloses the decomposition of hazardous materials by the use of microwaves enhanced by carbonaceous material, often activated carbon. The hazardous material is restricted to those organic compounds that are legally classified in this manner and not to material that could be classified as only harmful. A selected microorganism, pseudomonas bacteria, which is not a biological agent, was also decomposed. The process employs only a single microwave irradiated reactor containing carbonaceous material. The process shows that the required decomposition occurs either with a water or gaseous medium.